This invention relates generally to an excavation bucket for optimizing the cutting action thereby easily and quickly digging a trench or other excavation, such as a canal or drain. More particularly, a bucket for digging an excavation has both vertical and sloped sidewall areas with a cutting edge.
Digging deep and wide trenches usually required for footer construction in erecting buildings or for laying of large pipelines, or for irrigation ditches necessitates that several channel preparation passes be made. Excavations for small canals or drains or ditches for small pipelines may require only a single channel preparation pass be made. These passes or pass is generally made with an excavating bucket attached to a prime mover referred to as an excavator or backhoe or to similar equipment used in digging these trenches or excavations.
Some existing excavation bucket designs comprise vertical sidewalls with a lower cutting edge which cut the channel with vertical sides and a flat bottom resembling a retangular configuration. For safety standards and regulations, the channel dug by these designs must be reworked to give sloped sidewalls to eliminate the danger or likelihood of these vertical sidewalls from caving in, which could prove to be extremely hazardous and even fatal to a workman standing in these trenches, notwithstanding the extra time involved in redigging the trench.
Other existing excavation bucket designs provide for digging excavations with sloped sidewalls; however, they do not have the ability to dig the conventional vertical sidewall trenches which may be required in certain excavation applications. Also, the sloped walls of the excavation are usually substantially smooth thereby allowing erosion to occur.
Some examples of the sloped bucket design along with their operation are disclosed in U.S. Pat. Nos. 1,208,835; 2,972,425; 3,792,539; and 4,314,789. The bucket design exemplified in U.S. Pat. No. 3,792,539 issuing to Clark illustrates detachable wings mounted on opposite vertical side panels for digging excavations with either sloped sidewalls or conventional vertical sidewalls.
A drawback to the sloped sidewall bucket designs known in the art is that either vertical walls or sloped walls are formed in the excavation, and not both. In order for the Clark patent to perform one of these two functions, it is necessary to attach or detach the wings, which operation involves downtime resulting in decreased productivity. Some other drawbacks to all the sloped bucket designs of the known art is an increase in the resistance of these buckets in their movement through the earth due to the angle of the sidewalls and the bottom of the bucket, and also the interference in the maneuverability of these buckets which is due in part to their high center of gravity, which become particularly important in change over operations entailing the attachment and/or removal of these sloped buckets from the prime mover.
Another drawback to all the present sloped bucket designs particularly comes into play when pipe is laid in the sloped trenches in that the compaction force of the fill material on the pipe causes a wall of the pipe to cave inwardly producing an ovality condition for the pipe, which condition may be unacceptable according to safety standards.